Circuits Tool Box (Conclusions for Series and Parallel Circuit Lab)
Type of
Circuit
Path of
Electron
Voltage
Current
Equivalent Resistance
V
I
Req
Type of
Circuit
No Choice
Adds
Same
Req = R1 + R2 + R3
Series
1/Req = 1/R1 + 1/R2 + 1/R3
Parallel
Series
Parallel
Choice
Same for
Adds
each
branch
for each
branch
Best way to do Parallel Req is take the resisters 2 at a time and do POS (Product over Sum)
R1R2/(R1 + R2)
(Ohm’s Law)
V = IR
Voltage = Current * Resistance
P = IV
Power = Current * Voltage (also P = I2 * R)
Current = Brightness = Power (for a set voltage)
R is slope of Voltage-Current graph
P is area of rectangle of Voltage-Current graph
Powers of Resistances ALWAYS ADDS to = Power of Voltage Source
Resistance in wire is assumed zero. However in reality, the longer the wire is the more resistance it has. Also, the hotter a wire
is the more resistance it has.
Also: Ammeters measure Current going THROUGH wires and circuit elements are ALWAYS hooked in SERIES and
always have extremely LOW RESISTANCE. You have to BREAK a circuit and INSERT an Ammeter. Symbol is:
Voltmeters measure Voltage ACROSS wires and circuit elements and are ALWAYS hooked in Parallel and
always have extremely HIGH RESISTANCE. You NEVER BREAK a circuit and INSERT an Ammeter. Symbol is: